Graphene is a form of carbon having a hexagonal planar atomic lattice structure, as shown schematically in FIG. 1. Graphene has attracted a great deal of interest since 2004, when researchers found a simple way to produce isolated atomic planes of graphene and demonstrated a number of unique physical properties of such planes. The term “graphene” is often used in reference to atomic monolayers. Herein, however, we use the term more generally to apply to thin carbon films that have the graphene lattice structure and are thin enough, typically five or fewer atomic layers thick, that their electronic properties are dominated by the effects of reduced dimensionality and are therefore distinct from the electronic properties of bulk graphite.
Graphene is known to exhibit semiconductive or semimetallic electronic properties, as well as a direct band gap and high electron mobility. For that reason, among others, graphene is viewed as a candidate material-for transistors and integrated circuits.
Difficulties remain, however, in the production of graphene of sufficient quality and quantity, at low enough cost, to make its use in electronic devices commercially feasible.
The known techniques for making graphene films include mechanical exfoliation of graphite, epitaxial growth on suitable substrates, reduction from graphite oxide, precipitation from solutions of carbon in molten metal, and reduction of monomers such as sucrose or polymers such as polymethyl methacrylate (PMMA) on suitable substrates.
There is still a need, however, for a method of graphene synthesis that can form large films of uniform, controllable thickness at costs that are low enough to make this material industrially relevant.